Field
The present disclosure relates to a crystalline form of diethyl (RS)-1-(2,4-dichlorophenyl)-5-methyl-2-pyrazoline-3,5-dicarboxylate (mefenpyr-diethyl), to its preparation processes and to its use in agrochemical preparations.
Description of Related Art
Mefenpyr-diethyl, i.e., diethyl (RS)-1-(2,4-dichlorophenyl)-5-methyl-2-pyrazoline-3,5-dicarboxylate is a potent safener for sulfonylurea herbicides. Mefenpyr-diethyl has molecular formula of C16H18Cl2N2O4. Its chemical structure is:

It is typically used to reduce the phototoxicity of sulfonylurea herbicides when applied on crops, such as maize, wheat and cereals.
The commercially available mefenpyr-diethyl, which is usually manufactured by the process described in U.S. Pat. No. 5,703,008, which is incorporated herein by reference for all purposes, is present in an amorphous state.